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Question 1
Correct
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Which of the following is a function of Vitamin C?
Your Answer: Hydroxylation of proline to hydroxyproline for collagen synthesis
Explanation:Vitamin C acts as an electron donor for eight different enzymes: Three enzymes (prolyl-3-hydroxylase, prolyl-4-hydroxylase, and lysyl hydroxylase) that are required for the hydroxylation of proline and lysine in the synthesis of collagen.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 2
Incorrect
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A 82-year-old woman admitted following a fractured neck of femur has been discharged. On review, she is making good progress but consideration is given to secondary prevention of further fractures. What is the most appropriate step in the prevention of further fractures?
Your Answer: Arrange DEXA scan + start strontium ranelate if T-score < -2.5 SD
Correct Answer: Start oral bisphosphonate
Explanation:In such a clinical scenario, NICE guidelines support initiating treatment with bisphosphonates without waiting for a DEXA scan.Osteoporosis is defined as low bone mineral density caused by altered bone microstructure ultimately predisposing patients to low-impact, fragility fractures.Management:Vitamin D and calcium supplementation should be offered to all women unless the clinician is confident they have adequate calcium intake and are vitamin D repleteAlendronate is the first-line treatment. Around 25% of patients cannot tolerate alendronate, usually due to upper gastrointestinal problems. These patients should be offered risedronate or etidronate.Strontium ranelate and raloxifene are recommended if patients cannot tolerate bisphosphonates.Other medications that are useful in the treatment of osteoporosis are denosumab, teriparatide, raloxifene, etc.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 3
Correct
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The enzyme that catalyses the final step in glycogen synthesis is:
Your Answer: Glycogen synthase
Explanation:Glycogen synthase is a key enzyme in glycogenesis, the conversion of glucose into glycogen. This enzyme combines excess glucose residues one by one into a polymeric chain for storage as glycogen.
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 4
Correct
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Question 5
Correct
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All of the following features may suggest malignant changes in a melanocytic naevi, EXCEPT?
Your Answer: Decrease in size
Explanation:Melanocytic naevi are skin tumours produced by melanocytes. They usually present in childhood but increase during puberty. The mnemonic A-B-C-D, is used by institutions to assess for suspicion of malignancy. The letters stand for asymmetry, border, colour, and diameter. If a mole starts changing in size, colour, shape or, especially, if the border of a mole develops ragged edges or becomes larger than a pencil eraser, it would be an appropriate time to consult with a physician. Other warning signs include if it begins to crust over, bleed, itch, or become inflamed.
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This question is part of the following fields:
- Dermatology
- Medicine
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Question 6
Correct
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A 30-year-old agitated male was brought to the emergency department by his friend. Though there is little previous history, the friend believes that he has been suffering from depression for several years, and his medications have been changed by his general practitioner quite recently.On examination the patient is agitated and confused, his pupils are dilated. He also has tremors, excessive sweating, and grinding of teeth. His heart rate is 118 beats/min, which is regular, and is febrile with a temperature of 38.5°C.What is the most probable diagnosis?
Your Answer: Serotonin syndrome
Explanation:The most probable diagnosis in this patient is serotonin syndrome.The serotonin syndrome is a cluster of symptoms and signs (range from barely perceptible tremor to life-threatening hyperthermia and shock). It may occur when SSRIs such as citalopram, escitalopram, fluoxetine, fluoxetine, paroxetine, and sertraline that impair the reuptake of serotonin from the synaptic cleft into the presynaptic neuron are taken in combination with monoamine oxidase inhibitors or tricyclic antidepressants. It has also been reported following an overdose of selective serotonin reuptake inhibitors (SSRIs) alone.Treatment:Most cases of serotonin syndrome are mild and will resolve with removal of the offending drug alone. After stopping all serotonergic drugs, management is largely supportive and aimed at preventing complications. Patients frequently require sedation, which is best facilitated with benzodiazepines.Antipsychotics should be avoided because of their anticholinergic properties, which may inhibit sweating and heat dissipation.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 7
Incorrect
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Which of the following enzymes is mainly responsible for the hydrolysis of polysaccharide 1:6a linkages?
Your Answer: Maltase
Correct Answer: Isomaltase
Explanation:Isomaltase is mainly responsible for hydrolysis of 1:6α linkages. Along with maltase and sucrase, it also breaks down maltotriose and maltose.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 8
Incorrect
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Which receptor type is associated with uterine contracture in pregnancy?
Your Answer: M2
Correct Answer: Α1
Explanation:Alpha-1 adrenergic receptors cause uterine contraction during pregnancy. They are linked to Gq-proteins that activate smooth muscle contraction through the IP3 signal transduction pathway.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 9
Correct
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Which of the following conditions has no effect on cardiac output?
Your Answer: Sleep
Explanation:Sleep has no effect on the cardiac output. Anxiety, excitement and pregnancy will increase the cardiac output. Standing from a lying position will decrease the cardiac output transiently.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 10
Incorrect
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Which glucose transporter is responsible for the uptake of glucose in ß cells?
Your Answer: GLUT 4
Correct Answer: GLUT 2
Explanation:Glucose transporter 2, also known as GLUT2 is a transmembrane carrier protein which is not insulin dependent. It is found in the liver and the pancreatic islet ß cells, where it functions as the primary glucose transporter that allows the transfer of glucose between these organs and blood.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 11
Correct
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The pathway responsible for the discriminative aspect of pain, is called the:
Your Answer: Neospinothalamic tract
Explanation:The spinothalamic tract is an ascending or a sensory tract, responsible for transmission of pain and temperature. The neospinothalamic tract is responsible for fast pain or discriminative pain whereas the palaeospinothalamic tract is responsible for transmission of slow pain.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 12
Correct
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The pyloric sphincter is largely made up of thickening of
Your Answer: The circular muscle layer
Explanation:The pyloric sphincter, or valve, is a strong ring of smooth muscle (circular muscle layer) at the end of the pyloric canal which lets food pass from the stomach to the duodenum. It controls the outflow of gastric contents into the duodenum. It receives sympathetic innervation from the celiac ganglion.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 13
Incorrect
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The thalamic main input from the cortex is via which tracts?
Your Answer: Thalamospinal pathway
Correct Answer: Thalamocortical pathway
Explanation:The thalamus is connected to cerebral cortex via the thalamocortical radiation.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 14
Correct
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Portal vein receives its blood from all the following except:
Your Answer: Kidney
Explanation:The portal vein receives blood from the intestines via the superior and inferior mesenteric veins, from stomach via the gastric veins and from the spleen and pancreas via splenic vein. The kidney is supplied by the renal artery and drains into the renal vein into the inferior venacava.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 15
Incorrect
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Question 16
Correct
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Which of the following statements is true of the beta- lactams:
Your Answer: Co-amoxiclav is more likely to cause obstructive jaundice than amoxicillin
Explanation:β-lactam antibiotics are a class of broad-spectrum antibiotics, consisting of all antibiotic agents that contain a β-lactam ring in their molecular structures. This includes penicillin derivatives (penams), cephalosporins (cephems), monobactams, and carbapenems. Most β-lactam antibiotics work by inhibiting cell wall biosynthesis in the bacterial organism and are the most widely used group of antibiotics. Bacteria often develop resistance to β-lactam antibiotics by synthesizing a β-lactamase, an enzyme that attacks the β-lactam ring. To overcome this resistance, β-lactam antibiotics are often given with β-lactamase inhibitors such as clavulanic acid. Immunologically mediated adverse reactions to any β-lactam antibiotic may occur in up to 10% of patients receiving that agent (a small fraction of which are truly IgE-mediated allergic reactions). Rarely, cholestatic jaundice has been associated with Co-amoxiclav (amoxicillin/clavulanic acid). The reaction may occur up to several weeks after treatment has stopped, and usually takes weeks to resolve. It is more frequent in men, older people, and those who have taken long courses of treatment; the estimated overall incidence is one in 100,000 exposures.
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This question is part of the following fields:
- Infectious Diseases
- Medicine
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Question 17
Correct
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What is troponin?
Your Answer: A component of thin filaments
Explanation:Skeletal muscle cytoplasmic proteins include myosin and actin (also known as thick and thin filaments, respectively) which are arranged in a repeating unit called a sarcomere. Troponin is a component of thin filaments (along with tropomyosin), and is the protein to which calcium binds.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 18
Correct
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Telomerase is active in the following cells except:
Your Answer: Certain osteoblasts
Explanation:Some cells have the ability to reverse telomere shortening by expressing telomerase, an enzyme that extends the telomeres of chromosomes. Telomerase is an RNA-dependent DNA polymerase, meaning an enzyme that can make DNA using RNA as a template.
Telomerase is not usually active in most somatic cells (cells of the body), but it’s active in germ cells (the cells that make sperm and eggs) and some adult stem cells. These are cell types that need to undergo many divisions, or, in the case of germ cells, give rise to a new organism with its telomeric “clock” reset.Interestingly, many cancer cells have shortened telomeres, and telomerase is active in these cells. If telomerase could be inhibited by drugs as part of cancer therapy, their excess division (and thus, the growth of the cancerous tumor) could potentially be stopped.A subset of liver cells with high levels of telomerase renews the organ during normal cell turnover and after injury. -
This question is part of the following fields:
- Genetics
- Medicine
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Question 19
Correct
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Question 20
Correct
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Which intercellular connections are responsible for fastening the cells to one another?
Your Answer: Hemidesmosomes, zonula adherens & desmosomes
Explanation:There are three major types of cell junction:Adherens junctions, desmosomes and hemidesmosomes (anchoring junctions),Gap junctions (communicating junction) &Tight junctions (occluding junctions)
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 21
Correct
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In a newly diagnosed acromegaly patient, which of the following would you not expect to find?
Your Answer: Hypohidrosis
Explanation:Features of acromegaly may include:
- Soft tissue swelling visibly resulting in enlargement of the hands, feet, nose, lips and ears, and a general thickening of the skin
- Soft tissue swelling of internal organs, notably the heart with associated weakening of its muscularity, and the kidneys, vocal cords (resulting in a characteristic thick, deep voice and slowing of speech)
- Generalized expansion of the skull at the fontanelle, frontal bossing, prognathism with associated macroglossia (enlargement of the tongue) and teeth spacing.
- Hypertrichosis, hyperpigmentation and hyperhidrosis (not hypohidrosis) may occur in these patients as well as carpal tunnel syndrome and impotence.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 22
Correct
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Regarding cardiac muscle contractility, the afterload refers to:
Your Answer: The resistance against which blood is expected
Explanation:The afterload for the left ventricle is the aortic pressure. Hence it is this pressure that offers resistance against which the blood is to be expelled from the heart.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 23
Correct
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The net effect of active Vitamin D on calcium and phosphate homeostasis is?
Your Answer: Increase in Ca, increase in phosphate
Explanation:Bone and its metabolism are regulated by several hormones, amongst which is vitamin D. It is heavily involved in the metabolism and homeostasis of calcium and phosphate through several processes. Vitamin D works in the intestine, kidney, bone and parathyroid glands to maintain levels of calcium and phosphate, promoting its absorption, bone resorption, and proper functioning of the parathyroid to maintain adequate serum calcium levels.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 24
Incorrect
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A 24 year old man presents to the clinic complaining of lower limb joint pain and lower backache for the past 2 weeks. He remembers getting a mild gastrointestinal infection while in Spain 6 weeks ago that settled spontaneously. There has been eye irritation that has now settled. Past surgical history includes an appendectomy 3 years back. Vital examination shows a temperature of 37.5 C. Lab results reveal a normal WBC and raised ESR. Which of the following is true?
Your Answer: Aspirated synovial fluid from an inflamed joint will clinch the diagnosis
Correct Answer: Rheumatoid factor is likely to be negative
Explanation:Reactive arthritis, (formerly known as Reiter’s syndrome), is an autoimmune condition that occurs after a bacterial infection of the gastrointestinal or urinary tract. It is categorized as a seronegative spondylarthritis because of its association with HLA-B27. Reactive arthritis primarily affects young men and usually presents with musculoskeletal or extra‑articular symptoms. The characteristic triad consists of arthritis, conjunctivitis, and urethritis. The diagnosis is based on clinical features such as patient history and physical examination; there are no specific tests for reactive arthritis. Treatment is primarily symptomatic and consists of the administration of NSAIDs, as most patients recover spontaneously. extraarticular dermatologic manifestations include skin lesions of the glans resembling psoriasis (balanitis circinata); hyperkeratinisation of the palms and soles (keratoderma blenorrhagicum), oral ulcers. There usually is no rash and the diagnosis is unrelated to the presence of rheumatoid factor. This is a clinical diagnosis.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 25
Correct
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Which of the following conditions is procoagulant?
Your Answer: Factor V Leiden
Explanation:Factor V Leiden is a genetic mutation of one of the clotting factors in the blood, Factor V. This mutation makes Factor V resistant to inactivation by activated Protein C, which normally helps to regulate clot formation. As a result, individuals with Factor V Leiden are at increased risk of developing abnormal blood clots (thrombophilia), making it a procoagulant condition.
The other conditions listed are associated with bleeding tendencies rather than increased clotting:
- Afibrinogenemia: A rare genetic disorder where there is a complete lack of fibrinogen, leading to bleeding problems.
- Hemophilia: A group of inherited bleeding disorders where blood does not clot properly due to the lack of sufficient blood-clotting proteins (factors VIII or IX).
- Hypothrombinemia: A condition characterized by low levels of prothrombin, leading to increased bleeding.
- Christmas disease (Hemophilia B): A form of hemophilia caused by a deficiency of factor IX, resulting in a bleeding tendency.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 26
Incorrect
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Which glucose transporter is responsible for the uptake of dietary glucose from the gut?
Your Answer: GLUT1 45k
Correct Answer: SGLT1
Explanation:SGLT 1 is responsible for the uptake of glucose via secondary active transport from the small intestine and the renal tubules.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 27
Correct
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Which of the atrial pressure changes represents the a-wave of the JVP
Your Answer: Atrial systole
Explanation:The a-wave created on the venous pulse curve occurs as a result of atrial systole. Due to the pressure build-up in the atria, it causes a back pressure in the vena cava. This pressure is exerted on the valve and this back pressure is what causes a slight increase in the venous pressure.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 28
Correct
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Question 29
Correct
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Question 30
Correct
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A 24 year old male, known case of hereditary angioneurotic oedema presents with recurrent fever and arthralgia which is accompanied by a rash on face and upper chest. These attacks have been refractory to treatment and have occurred recurrently requiring adrenaline on several occasions. Lab results reveal persistently reduced C4 levels. Which of the following is most likely causing his current symptoms?
Your Answer: Systemic lupus erythematosus
Explanation:Angioedema secondary to C1 inhibitor deficiency has been rarely reported to be associated with systemic lupus erythematosus. A genetic defect of C1 inhibitor produces hereditary angioedema, which is usually presented with cutaneous painless oedema, but oedema of the genital area, gastrointestinal and laryngeal tracts have also been reported. In lupus patients, angioedema may be the result of an acquired type of C1 inhibitor deficiency, most probably due to antibody formation directed against the C1 inhibitor molecule.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 31
Correct
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The choroid plexus:
Your Answer: All are true
Explanation:The choroid plexus is a vascular structure found in all cerebral ventricles. The functional unit of the choroid plexus, composed of a capillary, enveloped by a layer of differentiated ependymal epithelium. Unlike the capillaries that form the blood-brain barrier, choroid plexus capillaries are fenestrated and have no tight junctions. The endothelium, therefore, does not form a barrier to the movement of small molecules. Instead, the blood-CSF barrier at the choroid plexus is formed by the epithelial cells and the tight junctions that link them.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 32
Incorrect
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The effects of β1 stimulation include the following
Your Answer:
Correct Answer: Increased strength of contraction
Explanation:β1 stimulation include the phosphorylation of L type Ca++ channels and phospholamban and increased Ca++ influx from myocytes.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 33
Incorrect
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Which of the following does not lower ventricular rate in atrial fibrillation?
Your Answer:
Correct Answer: Adrenaline
Explanation:Adrenaline is a sympathetic neurotransmitter which increases the heart rate. During atrial fibrillation the atria is contracting at more than 200 beats/min. Acetylcholine is a parasympathetic neurotransmitter decreasing the heart rate. Digital also depresses the conduction at the AV conduction. Vagal discharge and occulocardiac reflux decrease the heart rate and convert the tachycardia into normal sinus rhythm.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 34
Incorrect
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Translation usually begins at which codon?
Your Answer:
Correct Answer: AUG
Explanation:The start codon is the first codon of a messenger RNA (mRNA) transcript translated by a ribosome. The start codon always codes for methionine in eukaryotes and the most common start codon is AUG.
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 35
Incorrect
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Which one of the following have not been shown to improve mortality in patients with chronic heart failure?
Your Answer:
Correct Answer: Furosemide
Explanation:A number of drugs have been shown to improve mortality in patients with chronic heart failure:
- ACE inhibitors (SAVE, SOLVD, CONSENSUS)
- spironolactone (RALES)
- beta-blockers (CIBIS)
- hydralazine with nitrates (VHEFT-1)
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 36
Incorrect
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Within the hypothalamus, the dopamine-secreting neurones of the intrahypothalamic system have their cell bodies in which nuclei?
Your Answer:
Correct Answer: Arcuate
Explanation:Arcuate nucleus dopaminergic neurons consist of a single group of neurons that project to the median eminence where they release dopamine into the hypophyseal portal circulation to inhibit pituitary prolactin secretion.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 37
Incorrect
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What is the principle site of action of adrenocorticotrophic hormone (ACTH)?
Your Answer:
Correct Answer: Adrenal gland
Explanation:Adrenocorticotropic hormone, also known as ACTH or corticotropin, is a polypeptide tropic hormone. It is synthesized by the corticotropic cells of the anterior pituitary. It works by regulating the secretion of glucocorticoid hormones from the cortex cells in the adrenal gland. It binds to the melanocortin (MC) 2 receptors on the surface of the adrenal zona glomerulosa cells, producing cortisol.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 38
Incorrect
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Which segment of the nephron is impermeable to water?
Your Answer:
Correct Answer: Ascending limb of Henle
Explanation:Considerable differences aid in distinguishing the descending and ascending limbs of the loop of Henle. The descending limb is permeable to water and noticeably less permeable to salt, and thus only indirectly contributes to the concentration of the interstitium. Unlike the descending limb, the thin ascending limb is impermeable to water, a critical feature of the counter current exchange mechanism employed by the loop.
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This question is part of the following fields:
- Medicine
- Renal
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Question 39
Incorrect
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The neurotransmitter utilised by the Purkinje cells is:
Your Answer:
Correct Answer: GABA
Explanation:The cerebellar cortex consist of 3 layers: the molecular layer, the granular cell layer and the Purkinje cell layer. Purkinje cells play a fundamental role in controlling motor movement. They release a neurotransmitter called GABA (gamma-aminobutyric acid) which exerts inhibitory actions thereby reducing transmission of impulses. These inhibitory functions enable purkinje cells to regulate and coordinate motor movements.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 40
Incorrect
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Which of the following is a characteristic clinical finding of opioid poisoning?
Your Answer:
Correct Answer: Bradycardia
Explanation:Opioid poisoning is classically associated with pinpoint pupils, reduced respiratory rate, bradycardia, drowsiness and coma. Hypothermia is a feature of barbiturate poisoning, while sweating and lacrimation are seen in cases of opiate withdrawal.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 41
Incorrect
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What is the function of Activated protein C?
Your Answer:
Correct Answer: Inactivates factor Va
Explanation:Activated Protein C (APC) is a crucial protein in the regulation of blood coagulation. Its primary functions include:
- Inactivating Factor Va: APC inactivates Factor Va, which is a cofactor for the conversion of prothrombin to thrombin by Factor Xa. By inactivating Factor Va, APC reduces thrombin formation, thereby acting as an anticoagulant.
- Inactivating Factor VIIIa: APC also inactivates Factor VIIIa, another cofactor that assists Factor IXa in the conversion of Factor X to Factor Xa. This further contributes to its anticoagulant effect.
These actions help to regulate blood clotting and prevent excessive thrombosis.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 42
Incorrect
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The collection of genes that are termed the major histocompatibility complex (MHC) are found on:
Your Answer:
Correct Answer: Short arm of chromosome 6
Explanation:Histocompatibility, or tissue compatibility, is the property of having the same, or sufficiently similar, alleles of a set of genes called human leukocyte antigens (HLA). HLA is the human form of the major histocompatibility complex (MHC) genes found in all vertebrates. On a population level there is a great number of different alleles at each HLA locus on the short arm of chromosome 6
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This question is part of the following fields:
- Immunology
- Medicine
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Question 43
Incorrect
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Where in the gastrointestinal tract are valvulae conniventes?
Your Answer:
Correct Answer: Jejunum
Explanation:The circular folds (valves of Kerckring or valvulae conniventes) are large valvular flaps projecting into the lumen of the small intestine.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 44
Incorrect
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Depolarization spreads rapidly through cardiac muscle fibers because of the presence of:
Your Answer:
Correct Answer: Gap junctions
Explanation:The cardiac muscles have gap junctions in between the cells. They allow for the formation of low resistance passages, which allow ions to diffuse through every muscle fiber rapidly and result in the cardiac muscles functioning as a syncytium, without any protoplasmic bridges involved.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 45
Incorrect
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Which one of the following is not part of the WHO diagnostic criteria for the metabolic syndrome?
Your Answer:
Correct Answer: High LDL
Explanation:The World Health Organization 1999 criteria require the presence of any one of diabetes mellitus, impaired glucose tolerance, impaired fasting glucose or insulin resistance, AND two of the following:
- Blood pressure: ≥ 140/90 mmHg
- Dyslipidaemia: triglycerides (TG): ≥ 1.695 mmol/L and high-density lipoprotein cholesterol (HDL-C) ≤ 0.9 mmol/L (male), ≤ 1.0 mmol/L (female)
- Central obesity: waist: hip ratio > 0.90 (male); > 0.85 (female), or body mass index > 30 kg/m2
- Microalbuminuria: urinary albumin excretion ratio ≥ 20 µg/min or albumin: creatinine ratio ≥ 30 mg/g
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 46
Incorrect
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Di and tri peptides are absorbed via a different mechanism as amino acids, this is due to the working of which transporter?
Your Answer:
Correct Answer: PEPT 1
Explanation:GLUT and SGLT are glucose transporters. Peptides which are longer that four amino acids are not absorbed. There is abundant absorption of di and tri peptidases in the small intestine. They are absorbed into the epithelial cells of the small intestine via a transporter called PepT1 by co-transport with H+ ions.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 47
Incorrect
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Which part of the neuron has the highest concentration of sodium channels per square millimetre of the cell membrane?
Your Answer:
Correct Answer: Nodes of Ranvier
Explanation:The nodes of Ranvier contain Na+/K+ ATPases, Na+/Ca2+ exchangers and a high density of Na+ channels. The estimated concentration of sodium channels in the node is of ∼1500/μm2.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 48
Incorrect
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Concerning surface anatomy, where is the apex beat found?
Your Answer:
Correct Answer: 5th intercostal space mid clavicular line
Explanation:The location of the apex beat may vary but it is mostly found in the left 5th intercostal space 6 cm from the anterior median line or in the mid clavicular line.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 49
Incorrect
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Which serotonergic receptor is associated with vomiting?
Your Answer:
Correct Answer: 5ht3
Explanation:5ht3 is a receptor strongly associated with vomiting, present in vagal afferents, the solitary tract nucleus (STN), and the area posterior. For this reason, 5ht3 antagonists are commonly used as antiemetic drugs. They include ondansetron, tropisetron, and granisetron.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 50
Incorrect
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There is a measure of dispersion of a set of data from its mean. Which of following is the best term which can describe the above?
Your Answer:
Correct Answer: Standard deviation (root mean square deviation)
Explanation:Standard deviation is defined as the measure of dispersion of a set of data from its mean. It measures the absolute variability of a distribution; the higher the dispersion or variability, the greater is the standard deviation and greater will be the magnitude of the deviation of the value from their mean.
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This question is part of the following fields:
- Medicine
- Research Skills
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Question 51
Incorrect
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The predominant site in the lymph node where B lymphocytes are found is:
Your Answer:
Correct Answer: Cortex
Explanation:The cortex of the lymph node consists of the lymphoid nodules and sinusoids and posses a germinal centre from which B cells proliferate. The cortex of the lymph node predominately consists of B cells.
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This question is part of the following fields:
- Immunology
- Medicine
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Question 52
Incorrect
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A 64 year old woman who is of Asian descent and is diabetic (controlled by diet) presents with generalized body aches and difficulty rising from sitting for the last few months. Her blood glucose levels are in the normal range. Lab examination reveals normal blood cell count, low serum phosphate, calcium at the lower range, and raised alkaline phosphatase levels. Radiological examination shows which of the following?
Your Answer:
Correct Answer: Linear areas of low density
Explanation:Osteomalacia is a condition due to defective mineralization of osteoid. Occurs as a result of Vitamin D deficiency secondary to poor dietary intake and sun exposure, malabsorption e.g., inflammatory bowel disease and gastrointestinal bypass surgery. Radiological findings include reduced bone mineral density (a non specific finding), inability to radiologically distinguish vertebral body trabeculae (the film appears poor quality), looser pseudo fractures, fissures, or narrow radiolucent lines (these are the characteristic findings). Osteolytic or punched out lesions may be seen with multiple myeloma and bony metastases. Areas of sclerosis may be observed with conditions like osteosclerosis and Paget disease. A Brodie abscess is a subacute osteomyelitis, which may persist for years before progressing to a chronic, frank osteomyelitis.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 53
Incorrect
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Mutation in RB can lead to the formation of which cancer?
Your Answer:
Correct Answer: Retinoblastoma
Explanation:Patients with a history of autosomal dominant familial retinoblastoma have at least one mutated copy of the RB gene. This predisposes the patient to develop retinoblastoma in one or both the eyes. Patients with a family history should be screened properly so that it can be detected and treated as early as possible.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 54
Incorrect
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A 45 year old male presents with lower backache and pain in his hips. Blood tests are normal except for elevated serum alkaline phosphatase which is 1200 IU/l (45-105). Radiological examination shows combined osteolytic and osteosclerotic lesions. What is the most common site of occurrence of this disease?
Your Answer:
Correct Answer: Pelvis
Explanation:The patient most likely suffers from Paget’s disease of the bone as his radiological examination shows both osteolytic and osteosclerotic lesions. Any bone or bones can be affected, but Paget’s disease occurs most frequently in the pelvis > lumbar spine > femur > thoracic spine > sacrum > skull > tibia.
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This question is part of the following fields:
- Connective Tissue
- Medicine
-
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Question 55
Incorrect
-
An obstruction in a pulmonary artery causes impaired perfusion to an area in the lung. The gas values in the unperfused alveoli at sea level will be:
Your Answer:
Correct Answer: PO2 = 149 C02 =0
Explanation:Partial pressure of oxygen at sea level is approximately 160 mmHg. Partial pressure of oxygen in alveoli is around 150 mmHg and in an arteriole is around 80-100 mmHg. Partial pressure of carbon dioxide is around 35 mmHg in alveolar air and around 40 mmHg in the arteriole.
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This question is part of the following fields:
- Medicine
- Respiratory
-
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Question 56
Incorrect
-
Regarding cardiac output, an increased ejection fraction results from increases in which of the following?
Your Answer:
Correct Answer: Strength of contraction without increase in muscle fiber length
Explanation:When the strength of contraction increases without an increase in fiber length, the EF increases.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
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Question 57
Incorrect
-
Where is Müllerian inhibiting substance (MIS) secreted?
Your Answer:
Correct Answer: Sertoli cells
Explanation:Müllerian inhibiting substance, also known as Anti-Müllerian hormone (AMH) or Müllerian-inhibiting hormone (MIH) is a glycoprotein hormone which prevents the development of the Müllerian ducts into the uterus. Its production by Sertoli cells continues during childhood in males and decreases after puberty.
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This question is part of the following fields:
- Endocrinology
- Medicine
-
-
Question 58
Incorrect
-
When the heart rate is increased (to pathological levels) which of the following is correct when comparing the duration of diastole to systole?
Your Answer:
Correct Answer: It is shortened to a greater degree
Explanation:The duration of systole is more fixed than the duration of diastole. When the heart rate increases the timing of the systole remains more or less the same however diastole decreases.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
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Question 59
Incorrect
-
Café-au-lait spots are seen in each of the following, except:
Your Answer:
Correct Answer: Friedreich's ataxia
Explanation:Café-au-lait spots are hyperpigmented lesions that vary in colour from light brown to dark brown, with borders that may be smooth or irregular.
Causes include:
- Neurofibromatosis type I
- McCune–Albright syndrome
- Legius syndrome
- Tuberous sclerosis
- Fanconi anaemia
- Idiopathic
- Ataxia-telangiectasia
- Basal cell nevus syndrome
- Benign congenital skin lesion
- Bloom syndrome
- Chediak-Higashi syndrome
- Congenital nevus
- Gaucher disease
- Hunter syndrome
- Maffucci syndrome
- Multiple mucosal neuroma syndrome
- Noonan syndrome
- Pulmonary Stenosis
- Silver–Russell syndrome
- Watson syndrome
- Wiskott–Aldrich syndrome
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This question is part of the following fields:
- Dermatology
- Medicine
-
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Question 60
Incorrect
-
A 43 year old female presents with an array of symptoms including weakness, lethargy, dysphagia, dry mouth, gritty sensation in her eyes and increased photosensitivity. In order to confirm the suspected diagnosis, which of the following tests should be performed?
Your Answer:
Correct Answer: Labial gland biopsy
Explanation:To confirm the diagnosis, especially in patients with negative anti-Ro or anti-La antibodies, labial gland biopsy is done. In performing a labial biopsy, the surgeon typically makes a shallow 1/2 inch wide incision on either side of the inner lip after numbing the area with a local anaesthetic. Schirmer’s test determines whether the eye produces enough tears to keep it moist. This test can be done for ocular symptoms of Sjogren syndrome but is of no diagnostic importance as it can be positive with many other diseases.
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This question is part of the following fields:
- Connective Tissue
- Medicine
-
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Question 61
Incorrect
-
AV valves open during?
Your Answer:
Correct Answer: Early diastole
Explanation:The cardiac cycle refers to a complete heartbeat from its generation to the beginning of the next beat, and so includes the diastole, the systole, and the intervening pause.The first stage, diastole, is when the semilunar valves (the pulmonary valve and the aortic valve) close, the atrioventricular (AV) valves (the mitral valve and the tricuspid valve) open, and the whole heart is relaxed. The second stage, atrial systole, is when the atrium contracts, and blood flows from atrium to the ventricle.The third stage, isovolumic contraction is when the ventricles begin to contract, the AV and semilunar valves close, and there is no change in volume. The fourth stage, ventricular ejection, is when the ventricles are contracting and emptying, and the semilunar valves are open. During the fifth stage, isovolumic relaxation time, pressure decreases, no blood enters the ventricles, the ventricles stop contracting and begin to relax, and the semilunar valves close due to the pressure of blood in the aorta.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
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Question 62
Incorrect
-
There is normally an inverse relationship between the hepatic artery and portal venous blood flow. This is maintained by:
Your Answer:
Correct Answer: All of the options are correct
Explanation:There is an inverse relationship between the blood flow of the hepatic artery and portal vein. It is maintained by several factors such as chemicals like adenosine, neurohumoral substances, the morphology of the hepatic portal system (especially the ability of hepatic sinusoids to collapse) and myogenic control which causes vasoconstriction or vasodilation.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
-
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Question 63
Incorrect
-
The interstitium of the kidney is most hypertonic in the:
Your Answer:
Correct Answer: Papillary tip of the medulla
Explanation:The medullary interstitium is the tissue surrounding the loop of Henle in the renal medulla. It functions in renal water reabsorption by building up a high hypertonicity, which draws water out of the thin descending limb of the loop of Henle and the collecting duct system. This hypertonicity, in turn, is created by an efflux of urea from the inner medullary collecting duct.
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This question is part of the following fields:
- Medicine
- Renal
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Question 64
Incorrect
-
Question 65
Incorrect
-
Catecholamines…
Your Answer:
Correct Answer: Activate adenylyl cyclase
Explanation:Norepinephrine and epinephrine activate or deactivate adenylyl cyclase resulting in a decrease or an increase in the production of cAMP.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
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Question 66
Incorrect
-
In a normal heart rate at rest, the left ventricular end-diastolic volume is ….
Your Answer:
Correct Answer: 100-130 ml
Explanation:In cardiovascular physiology, end-diastolic volume (EDV) is the volume of blood in the right and/or left ventricle at end load or filling in (diastole) or the amount of blood in the ventricles just before systole. Because greater EDVs cause greater distention of the ventricle, EDV is often used synonymously with preload, which refers to the length of the sarcomeres in cardiac muscle prior to contraction (systole). End-diastolic volume: Right = 144 mL(± 23mL) & Left = 142 mL (± 21 mL).
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
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Question 67
Incorrect
-
Where does most fat digestion begin?
Your Answer:
Correct Answer: Duodenum
Explanation:Digestion of some fats can begin in the mouth where lingual lipase breaks down some short chain lipids into diglycerides. However fats are mainly digested in the small intestine (in the duodenum). The presence of fat in the small intestine produces hormones that stimulate the release of pancreatic lipase from the pancreas and bile from the liver which helps in the emulsification of fats for absorption of fatty acids.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
-
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Question 68
Incorrect
-
The layers of the neocortex from the 1st to the 6th are arranged as follows:
Your Answer:
Correct Answer: Molecular, external granular, external pyramidal, internal granular, internal pyramidal, multiform
Explanation:The layers of neocortex from outermost to innermost include: the molecular, external granular layer, external pyramidal, internal granular, internal pyramidal and multiform layer.
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This question is part of the following fields:
- Medicine
- Neurology
-
-
Question 69
Incorrect
-
Cholinergic nerves from the vagus innervate the SA and AV nodes via which receptor in the heart?
Your Answer:
Correct Answer: M2 receptor
Explanation:M2 receptor is found in the heart. M3 and M4 are associated with smooth muscle.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
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Question 70
Incorrect
-
Which intestinal cells play a major role in secretory immunity?
Your Answer:
Correct Answer: M cells
Explanation:M cells are specialized epithelial cells of the MALT or mucosa-associated lymphoid tissues. They transport antigens from the intestinal lumen to cells of the immune system, thereby initiating an immune response. T and B cells are lymphocytes found in blood. Mucous cells secrete mucous and can be considered as a part of innate immunity. Chief cells in the gastric mucosa secret pepsin.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
-
-
Question 71
Incorrect
-
The functional unit of the liver is called?
Your Answer:
Correct Answer: Acini
Explanation:From a metabolic perspective, the functional unit is the hepatic acinus (terminal acinus), each of which is centred on the line connecting two portal triads and extends outwards to the two adjacent central veins. The periportal zone I is nearest to the entering vascular supply and receives the most oxygenated blood, making it least sensitive to ischemic injury while making it very susceptible to viral hepatitis. Conversely, the centrilobular zone III has the poorest oxygenation, and will be most affected during a time of ischemia.
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This question is part of the following fields:
- Hepatobiliary
- Medicine
-
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Question 72
Incorrect
-
The initial rapid depolarization in the action potential of cardiac muscle cells is due to:
Your Answer:
Correct Answer: Opening of voltage-gated Na+ channels
Explanation:The initial depolarization of the action potential in a cardiac muscle cell is due to the sodium current generated by opening of the voltage gated sodium channels leading to an influx of sodium ions into the cell and raising the membrane potential towards threshold.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 73
Incorrect
-
Which receptor type is associated with the inhibition of pancreatic endocrine secretion?
Your Answer:
Correct Answer: Α2
Explanation:The activation of alpha 2-adrenergic receptors in pancreatic beta-cells works by inhibiting the secretion of insulin.
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This question is part of the following fields:
- Medicine
- Neurology
-
-
Question 74
Incorrect
-
Visual pathways - Choose the true statement:
Your Answer:
Correct Answer: The lateral geniculate nucleus, magnocellular & parvocellular pathways project to the primary visual cortex
Explanation:The optic chiasm is made by the decussation of optic fibers on the nasal side. The magnocellular pathway carries signals for detection of movement. The parvocellular pathway carries cells for detection of shape, size, colour and clarity. The lateral geniculate nucleus (LGN) is the relay centre in the thalamus for he visual pathway. It has layers of magnocellular cells and parvocellular cells that are interleaved with layers of koniocellular cells. The LGN is the main central connection for the optic nerve to the occipital lobe, particularly the primary visual cortex.
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This question is part of the following fields:
- Medicine
- Neurology
-
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Question 75
Incorrect
-
Which of the following would be a contraindication to thrombolysis?
Your Answer:
Correct Answer: Intracranial neoplasm
Explanation:Absolute contraindications to thrombolysis include:
- Previous intracranial bleeding at any time
- Stroke in less than 6 months
- Closed head or facial trauma within 3 months
- Suspected aortic dissection
- Ischemic stroke within 3 months (except in ischemic stroke within 3 hours time)
- Active bleeding diathesis
- Uncontrolled high blood pressure (>180 systolic or >100 diastolic)
- Known structural cerebral vascular lesion
- Arterio-venous malformations
- Thrombocytopenia
- Known coagulation disorders
- Aneurysm
- Brain tumours
- Pericardial effusion
- Septic embolus
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 76
Incorrect
-
A 85 year old male with a history of Alzheimer's dementia was brought into Casualty by family members, who stated that he had episodes of aggression. Which of the following drugs is most suitable as the pharmacological management for this presentation?
Your Answer:
Correct Answer: Risperidone
Explanation:Regarding the pharmacological management, Risperidone is the most suitable drug from the given answers as it is recommended for the treatment of aggression associated with moderate to severe Alzheimer’s disease. Quetiapine and Benzodiazepine are not recommended.
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This question is part of the following fields:
- Geriatrics
- Medicine
-
-
Question 77
Incorrect
-
Where in the course of the gastrointestinal tract does the first significant digestion of fat begin in a normal human being?
Your Answer:
Correct Answer: Duodenum
Explanation:The enzyme lipase which is responsible for digestion of fat is secreted by the exocrine pancreas in the 2nd part of the duodenum at the point where the pancreatic duct opens. It opens together with the common bile duct which contains bile that emulsify fat aiding in digestion. The oesophagus, stomach and mouth do not contain enzymes related to fat digestion.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
-
-
Question 78
Incorrect
-
Antibiotic resistance may happen by:
Your Answer:
Correct Answer: By enzymes which inactivate the drug
Explanation:The three main mechanisms of antibiotic resistance are, enzymatic degradation of antibacterial drugs, alteration of bacterial proteins that are antimicrobial targets, and changes in membrane permeability to antibiotics.
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This question is part of the following fields:
- Infectious Diseases
- Medicine
-
-
Question 79
Incorrect
-
The following are Gram positive rods:
Your Answer:
Correct Answer: Clostridia
Explanation:Examples of Gram positive bacilli:Bacillus genusClostridium genusCorynebacterium genusListeria genusPropionibacterium genusExamples of Gram negative bacilli:Bacteroides genusCitrobacter genusEnterobacter genusEscherichia genusPseudomonas genusProteus genusSalmonella genusSerratia genusShigella genusYersinia genus
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This question is part of the following fields:
- Infectious Diseases
- Medicine
-
-
Question 80
Incorrect
-
Activation of baroreceptor reflex involves:
Your Answer:
Correct Answer: Short term regulation of systemic blood pressure
Explanation:Baroreceptors are found in the heart and the blood vessels. They are the carotid sinus and the aortic arch receptors and respond to the minute to minute change in the blood pressure i.e. a change in the pulsatile pressure and not to a change in the mean arterial pressure. If the pulse pressure decreases, the rate of firing of the receptors decreases, stimulating an increase in the heart rate and blood pressure. Mechanisms that regulate the long term blood pressure control include the renin-angiotensin-aldosterone mechanism.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 81
Incorrect
-
Which lipoprotein contains the most cholesterol esters?
Your Answer:
Correct Answer: LDL
Explanation:LDL and HDL transport both dietary and endogenous cholesterol in the plasma, but LDL is the main transporter of cholesterol and cholesteryl esters.
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This question is part of the following fields:
- Medicine
- Metabolism
-
-
Question 82
Incorrect
-
The enzyme responsible for Telomeres to maintain their length after cell division is called:
Your Answer:
Correct Answer: Telomerase reverse transcriptase
Explanation:Telomeres are non-coding DNA consisting of repetitive nucleotide sequences plus proteins that are found at the end of the linear chromosomes. They maintain the integrity of the chromosomes and prevent their shortening.
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This question is part of the following fields:
- Genetics
- Medicine
-
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Question 83
Incorrect
-
Choose the correct statement regarding the protein C/S system?
Your Answer:
Correct Answer: The protein C/S complex inactivates factor Va and VIIIa
Explanation:The best characterized function of Protein S is its role in the anti coagulation pathway, where it functions as a cofactor to Protein C in the inactivation of Factors Va and VIIIa.
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This question is part of the following fields:
- Haematology
- Medicine
-
-
Question 84
Incorrect
-
Question 85
Incorrect
-
An 81 year old male patient was admitted after an ischaemic stroke. Physical examination reveals left hemiparesis. How would you classify this hemiparesis based on the WHO International Classification of Functioning, Disability and Health?
Your Answer:
Correct Answer: Impairment of body function
Explanation:Symptoms and signs are classified as ‘impairment of body function’. The types of impairment classified as ‘activity limitation’ include difficulties that a patient may have in executing certain activities. The type of impairment classified as ‘participation restriction’ are problems a patient may have in social roles. The type of impairment classified as ‘pathology’ would be the diagnosis/disease. Right total anterior circulation infarct relates to the Oxford Bamford classification for stroke.
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This question is part of the following fields:
- Geriatrics
- Medicine
-
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Question 86
Incorrect
-
Following an action potential, cytosolic Ca2+ is increased. The binding of free Ca2+ to troponin C results in all of the following except:
Your Answer:
Correct Answer: Weakening of the troponin i interaction with actin
Explanation:At rest, troponin i is bound to actin and tropomyosin and covers the site where the myosin head interacts with actin. When Calcium enters into the muscle, it binds with troponin C and cause a structural change in troponin i which moves out of the myosin binding site and causes the cross bridges between the actin and myosin filaments to occur.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 87
Incorrect
-
A 22-year-old university student is admitted after taking drugs at a night club. Which of the following features suggest she had taken ecstasy (MDMA)?
Your Answer:
Correct Answer: A pyrexia of 40°C
Explanation:MDMA commonly known as ecstasy or molly, is a psychoactive drug primarily used as a recreational drug. The desired effects include altered sensations, increased energy, empathy, and pleasure. Features of MDMA abuse include hyponatraemia, tachycardia, hyperventilation, and hyperthermia.
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This question is part of the following fields:
- Medicine
- Pharmacology
-
-
Question 88
Incorrect
-
A 18-year-old female is brought to the emergency department by her boyfriend. He is concerned that she may have taken an overdose of her mom's morphine sulphate pills after being depressed about her mother, who is dying of carcinoma of the breast.Which of the following may point towards his suspicion?
Your Answer:
Correct Answer: Sweating
Explanation:Excessive sweating points towards a morphine overdose.Morphine is considered the classic opioid analgesic with which other painkillers are compared. Like other medications in this class, morphine has an affinity for delta, kappa, and mu-opioid receptors.Most commonly used in pain management, morphine provides major relief to patients afflicted with pain.Among the more common adverse effects of morphine use is constipation. Other side effects include nausea, vomiting, drowsiness, and confusion. Psychological and physical dependence may occur.Other side effects include bronchospasm, angioedema, urinary retention, ureteric or biliary spasm, dry mouth, sweating, rash, facial flushing, vertigo, tachycardia, bradycardia, palpitations, orthostatic hypotension, hypothermia, restlessness, mood change, hallucinations, seizures (adults and children) and miosis, headache and allergic reactions (including anaphylaxis) and decreased libido or potency.Raised intracranial pressure occurs in some patients. Muscle rigidity may occur with high doses. Elevated liver enzymes may occur due to biliary sphincter constriction. Large doses can lead to respiratory depression, circulatory failure, and coma.Treatment of opioid overdose:Initial treatment of overdose begins with supportive care.Naloxone is a pure competitive antagonist of opiate receptors and has no agonistic activity. The drug is relatively safe and can be administered intravenous, intramuscular, subcutaneous or via the endotracheal tube.Alternatively, nalmefene and naltrexone maybe considered.
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This question is part of the following fields:
- Medicine
- Pharmacology
-
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Question 89
Incorrect
-
A 62 year old female has complained she feels unsteady when she is walking. She is examined and is found to have pyramidal weakness of her left lower leg. She also has reduced pain and temperature sensation on her right leg and right side of her torso up to the umbilicus. Her joint position sense is also impaired in her left big toe but is found to be normal elsewhere. She has definite left extensor plantar response, and the right plantar response is equivocal. Where is the lesion?
Your Answer:
Correct Answer: Left mid-thoracic cord
Explanation:In Brown-Sequard syndrome, there is paralysis and loss of proprioception, which occurs on the same (ipsilateral) side of the body, as the lesion. Loss of pain and temperature sensation, therefore, occurs on the opposite (contralateral) side of the body as the lesion.
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This question is part of the following fields:
- Geriatrics
- Medicine
-
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Question 90
Incorrect
-
Regarding the innervation of cerebral blood vessels, which of the following triggers a vasoconstrictor effect?
Your Answer:
Correct Answer: Neuropeptide-Y
Explanation:Substance P is a potent vasodilator, VIP or vasoactive intestinal peptide has vasodilator properties in the intestines. PHM 27 is a potent calcitonin receptor agonist; endogenous analogue of human VIP. CGRP or Calcitonin Gene-Related Peptide is a vasodilator which is found to play an important role in migraines. Neuropeptide Y is a strong vasoconstrictor.
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This question is part of the following fields:
- Medicine
- Neurology
-
-
Question 91
Incorrect
-
Select the correct statement about the microanatomy of the thyroid gland.
Your Answer:
Correct Answer: The capillaries adjacent to thyroid cells have a fenestrated endothelium.
Explanation:Fenestrated capillaries have a very thin endothelium, which is perforated by numerous fenestrations or pores. Hormones are usually released into these capillaries, reaching their target cells through the circulatory system.
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This question is part of the following fields:
- Endocrinology
- Medicine
-
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Question 92
Incorrect
-
The Cellular Theory of Ageing involves?
Your Answer:
Correct Answer: Loss of telomeres
Explanation:Cellular theories of aging propose that human aging is the result of cellular aging, whereby an increasing proportion of cells reach senescence, a terminal stage at which cells will cease to divide. This will limit the body’s ability to regenerate and to respond to injury or stress. Telomeres are bits of DNA on the ends of chromosomes that protect chromosomes from sticking to each other or tangling, which could cause DNA to abnormally function. As cells replicate, telomeres shorten at the end of chromosomes, and this process correlates to senescence or cellular aging.
Other theories include:
- The Free Radical Theory: Implicates the gradual accumulation of oxidative cellular damage as a fundamental driver of cellular aging. This theory has evolved over time to emphasize the role of free radical induced mitochondrial DNA (mtDNA) mutations and the accumulation of mtDNA deletions. Given the proximity of mtDNA to the electron transport chain, a primary producer of free radicals, it postulates that the mutations would promote mitochondrial dysfunction and concomitantly increase free radical production in a positive feedback loop. It is known that diet, lifestyle, drugs (e.g. tobacco and alcohol) and radiation etc., are all accelerators of free radical production within the body.
- Error theory: based on the idea that errors can occur in the transcription of the synthesis of DNA. These errors are perpetuated and eventually lead to systems that do not function at the optimum level. The organism’s aging and death are attributable to these events (Sonneborn, 1979).
- The Cross-Linking Theory: also referred to as the Glycosylation Theory of Aging. In this theory it is the binding of glucose (simple sugars) to protein, (a process that occurs under the presence of oxygen) that causes various problems. Once this binding has occurred the protein becomes impaired and is unable to perform as efficiently. Living a longer life is going to lead to the increased possibility of oxygen meeting glucose and protein and known cross-linking disorders include senile cataract and the appearance of tough, leathery and yellow skin.
- The Neuroendocrine Theory First proposed by Professor Vladimir Dilman and Ward Dean MD, this theory elaborates on wear and tear by focusing on the neuroendocrine system. This system is a complicated network of biochemicals that govern the release of hormones which are altered by the walnut sized gland called the hypothalamus located in the brain. The hypothalamus controls various chain-reactions to instruct other organs and glands to release their hormones etc. The hypothalamus also responds to the body hormone levels as a guide to the overall hormonal activity. But as we grow older the hypothalamus loses it precision regulatory ability and the receptors which uptake individual hormones become less sensitive to them. Accordingly, as we age the secretion of many hormones declines and their effectiveness (compared unit to unit) is also reduced due to the receptors down-grading
- The Membrane Theory of Aging: According to this theory it is the age-related changes of the cell’s ability to transfer chemicals, heat and electrical processes that impair it. As we grow older the cell membrane becomes less lipid (less watery and more solid). This impedes its efficiency to conduct normal function and in particular there is a toxic accumulation
- The Decline Theory: The mitochondria are the power producing organelles found in every cell of every organ. Their primary job is to create Adenosine Triphosphate (ATP) and they do so in the various energy cycles that involve nutrients such as Acetyl-L-Carnitine, CoQ10 (Idebenone), NADH and some B vitamins etc. Enhancement and protection of the mitochondria is an essential part of preventing and slowing aging. Enhancement can be achieved with the above mention nutrients, as well as ATP supplements themselves.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 93
Incorrect
-
G cells release which of the following substances
Your Answer:
Correct Answer: Gastrin
Explanation:The G cell is a type of cell in the stomach and duodenum that secretes gastrin. It works in conjunction with gastric chief cells and parietal cells. G cells are found deep within the pyloric glands of the stomach antrum, and occasionally in the pancreas and duodenum. Gastrin-releasing peptide, as well as the presence of amino acids in the stomach, stimulates the release of gastrin from the G cells. Gastrin stimulates enterochromaffin-like cells to secrete histamine. Gastrin also targets parietal cells by increasing the amount of histamine and the direct stimulation by gastrin, causing the parietal cells to increase HCl secretion in the stomach.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
-
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Question 94
Incorrect
-
Which of the following statements regarding psoriasis is incorrect?
Your Answer:
Correct Answer: Mediated by type 2 helper T cells
Explanation:Psoriasis is a long-lasting autoimmune disease which is characterized by patches of abnormal skin. These skin patches are typically red, itchy, and scaly commonly on the extensor surfaces. Psoriasis is associated with an increased risk of psoriatic arthritis, lymphomas, cardiovascular disease, Crohn’s disease, and depression. Psoriatic arthritis affects up to 30% of individuals with psoriasis. Psoriasis is mediated by type 1 helper T cells which are involved in the cell mediated response, rather than type 2 helper T cells
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This question is part of the following fields:
- Dermatology
- Medicine
-
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Question 95
Incorrect
-
A 27-year-old man presents with a regular tachycardia of 190 bpm. He is healthy and has no past medical history. Blood pressure and blood tests are all within normal parameters however the ECG confirms a narrow complex tachycardia. The tachycardia persists after giving IV adenosine 6mg. What should be the next step in management of this patient?
Your Answer:
Correct Answer: IV 12mg adenosine
Explanation:For narrow complex tachycardias with no compromise then vagal manoeuvres should be trialled first. The Valsalva manoeuvre should be the first vagal manoeuvre tried and works by increasing intra-thoracic pressure and affecting baroreceptors (pressure sensors) within the arch of the aorta. It is carried out by asking the patient to hold his/her breath while trying to exhale forcibly as if straining during a bowel movement. Adenosine, an ultra-short-acting AV nodal blocking agent, is indicated if vagal manoeuvres are not effective. Adenosine may be safely used during pregnancy. In adults the recommended first dose of intravenous adenosine is 6 mg. The dose is administered rapidly and then followed by a saline flush. Adenosine is only present in the circulation for about 5 seconds, so it is an excellent drug for diagnosis and treatment. If there was a response to adenosine but it was not long lasting, an additional dose of 12 mg of adenosine intravenously can be attempted. Doses greater than 12 mg are not recommended. If adenosine fails then Verapamil or a beta blocker can be used as alternatives. If the patient is hemodynamically unstable or other treatments have not been effective, synchronized electrical cardioversion may be used.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
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Question 96
Incorrect
-
Which of the following is first to rise following myocardial infarction?
Your Answer:
Correct Answer: Myoglobin
Explanation:Myoglobin, is a sensitive indicator of muscle injury and is first to rise following MI within two hours but is nonspecific.Troponin and CK-MB both begin to rise approximately three hours after MI. The cardiac troponins T and I which are released within 4–6 hours of an attack of MI and remain elevated for up to 2 weeks, have nearly complete tissue specificity and are now the preferred markers for assessing myocardial damage.Lactate dehydrogenase (LDH) begins to rise approximately 12 hours after MI.
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This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 97
Incorrect
-
Where is the major site of purine synthesis?
Your Answer:
Correct Answer: Liver
Explanation:The major site of purine synthesis is in the liver. Purines are biologically synthesized as nucleotides and in particular as ribotides.
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This question is part of the following fields:
- Medicine
- Metabolism
-
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Question 98
Incorrect
-
A sarcomere is the area between:
Your Answer:
Correct Answer: Two adjacent z lines
Explanation:The area that lies between the two adjacent Z lines is known as a sarcomere and is the contractile unit of the muscle. The line passing in the middle of the myosin filaments is the M line. It also passes through the middle of the sarcomere.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 99
Incorrect
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A 30-year-old female presents with a 4-day history of diarrhoea and vomiting. She has been unable to keep fluids down for 4 days and has been treated with metoclopramide. She develops a dystonic reaction. What is the most appropriate treatment for this woman?
Your Answer:
Correct Answer: Benztropine
Explanation:Acute dystonic reactions (extrapyramidal symptoms) such as spasmodic torticollis, trismus, and oculogyric crises can occur following the administration of metoclopramide or stemetil and thus, neither is recommended for the treatment of nausea in young women.
Such reactions respond well to treatment with benztropine or procyclidine.
– Benztropine: It is an anticholinergic medication with significant CNS penetration. A single dose of benztropine 1 to 2 mg IV followed by 1 to 2 mg p.o twice a day for up to 7 days to prevent a recurrence. Subsequently, both the offending agent and those from the same group should be avoided.
– Alternatively, diphenhydramine can be used intravenously (up to a dose of 50mg) or intramuscularly followed by p.o therapy every 6 hours for 1 to 2 to prevent a recurrence.- Second-line therapy with IV benzodiazepines is reserved for those patients who do not respond to anticholinergics.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 100
Incorrect
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Regarding the anatomy of the intestine, the muscularis propria contains all of which of the following constituents?
Your Answer:
Correct Answer: Circular muscle, myenteric plexus, longitudinal muscle
Explanation:The muscularis mucosa/propria consists of the inner circular muscles and the outer longitudinal muscles. Between these muscles is the myenteric plexus.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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